Screw-cutting die.



No. 707,233. Patented Aug. 19,1902.

, c. J. JACKSON.

SCREW CUTTING DIE.

(Application filed Oct. 6, 1300.)

(No Model. 7

WITNESSES; mvz r00" ATTORNEY.

nu: nonms PETER: c0. PNOTO-UTHO.. wnsnmamu, 04 c I UNITED STATES PATENT OFFICE.

CHARLES J. JACKSON, OF ERIE, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO REUBEN G. WRIGHT, OF WESTFIELD, NEW YORK.

SCREW-CUTTING DIE.

SPECIFICATION formingpart of Letters Patent N 0. 707,233, dated August 19, 1902.

' Application filed October 5,1900. Serial No. 32,112. (No model.)

;. all whom/it may concern;

Be it known that I, CHARLES J. JACKSON,

a citizen of the United States, residing at Erie, in the county of Erie and State of Pennsyl- Vania, have invented certain new and useful Improvements in Screw-Cutting Dies; and I do hereby'declare the following to be a full,

clear, and exact description of the invention,

such as will enable others skilled in the art :0 to which it appertains to make and use the same.

This invention relates to screw-cutting dies'i' and it consists in certain improvements in the construction thereof, as will be hereinafx5 for fully described, and pointed out in the claim.

The invention is illustrated in the accompanying drawings, as follows:

Figure 1 shows a side elevation of the die. Fig. 2 shows a section on the line 2 2 in Fig. 1. A marks the die-plate; B, the chasers. In the manufacture of these the chasers are placed in the molds and are secured in place as the plate A is cast. The chasersareiafterward cut and ground as desired. Dieplates of this general construction have been heretofore made-that is, the chasers have been secured in the plate as the plates were cast. As far as I am aware, however, with all such constructions the faces of the chasers have been at right angles to the face of, the

plate A. With my construction I have placed the chasers at right angles to the plate A, so that the front edges of the thread-cutting 3 5 teeth are slightly in advance of the rear edges. This gives a clearance to the cutting edge. Most pipes and other articles which are to be screw-threaded are of more or less uneven surface. Usually smallribs .are formed in the process of manufacturing pipes and rods.

These ribs are usually parallel with the axis of the pipe or rod. By placing the chasers B at a slight inclination thedifferent teeth strike the ribs at different times-that is, the

chaser does not present asquare shoulder to a rib, and consequently a more even cutting actionis produced.

As a further improvement of my invention I have formed the plate A with the portion a-immediately in advance'of the chaser of greater depth than that a immediately at the rear of the chaser. The portion a (cut away) gives clearance for the passage of chips, and'the shoulder or portion a braces the chaser, so as to prevent its spring.

In a cast die, as shown, the shoulder a forms a body of metal adjacent to the chaser, and consequently as the die is tempered holds the heat in this portion of the chaser for a longer period than the cutting-face, and thus 6o gives to that portion of the chaser less temper than at the cutting edge, so that while the clearance remains sufficient this shoulder not only braces the chaser, but gives tothat part of the'chaser receiving the strain greater CHARLES J. JACKSON.

WVitnesses: I N

FRANK W. BAO N; ZARLIN PAUL. 

